Framework for EVPN Designated Forwarder Election Extensibility
draft-ietf-bess-evpn-df-election-framework-03

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BESS Workgroup                                           J. Rabadan, Ed.
Internet Draft                                                     Nokia
                                                         S. Mohanty, Ed.
Intended status: Standards Track                              A. Sajassi
                                                                   Cisco
                                                                J. Drake
                                                                 Juniper
                                                              K. Nagaraj
                                                            S. Sathappan
                                                                   Nokia

Expires: November 25, 2018                                  May 24, 2018

     Framework for EVPN Designated Forwarder Election Extensibility
             draft-ietf-bess-evpn-df-election-framework-03

Abstract

   The Designated Forwarder (DF) in EVPN networks is the PE responsible
   for sending broadcast, unknown unicast and multicast (BUM) traffic to
   a multi-homed CE, on a given VLAN on a particular Ethernet Segment
   (ES). The DF is selected out of a list of candidate PEs that
   advertise the same Ethernet Segment Identifier (ESI) to the EVPN
   network. By default, EVPN uses a DF Election algorithm referred to as
   "Service Carving" and it is based on a modulus function (V mod N)
   that takes the number of PEs in the ES (N) and the VLAN value (V) as
   input. This default DF Election algorithm has some inefficiencies
   that this document addresses by defining a new DF Election algorithm
   and a capability to influence the DF Election result for a VLAN,
   depending on the state of the associated Attachment Circuit (AC). In
   addition, this document creates a registry with IANA, for future DF
   Election Algorithms and Capabilities. It also presents a formal
   definition and clarification of the DF Election Finite State Machine.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
 

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   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

   This Internet-Draft will expire on November 24, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document. Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

 

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Table of Contents

   1. Conventions and Terminology . . . . . . . . . . . . . . . . . .  3
   2. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1. Default Designated Forwarder (DF) Election in EVPN  . . . .  4
     2.2. Problem Statement . . . . . . . . . . . . . . . . . . . . .  5
       2.2.1. Unfair Load-Balancing and Service Disruption  . . . . .  6
       2.2.2. Traffic Black-Holing on Individual AC Failures  . . . .  7
     2.3. The Need for Extending the Default DF Election in EVPN  . .  9
   3. Designated Forwarder Election Protocol and BGP Extensions . . . 10
     3.1 The DF Election Finite State Machine (FSM) . . . . . . . . . 10
     3.2 The DF Election Extended Community . . . . . . . . . . . . . 13
     3.3 Auto-Derivation of ES-Import Route Target  . . . . . . . . . 15
   4. The Highest Random Weight DF Election Type  . . . . . . . . . . 15
     4.1. HRW and Consistent Hashing  . . . . . . . . . . . . . . . . 16